Genetic Testing in a Patient With Suspected Hyperparathyroidism- Jaw Tumor Syndrome (HPT-JT)

Introduction: Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is a rare autosomal dominant disorder characterized by parathyroid tumors in association with fibro-osseous jaw tumors, uterine tumors and renal lesions. We present a case of suspected HPT-JT. Clinical Case: A 50-year-old female with suspected HPT-JT was referred for treatment of osteoporosis. Patient was initially diagnosed with osteosarcoma in 1980 at age 10, and underwent resection with leg amputation and chemotherapy. Around 1995, she was found to have primary hyperparathyroidism secondary to a parathyroid adenoma and underwent one gland parathyroidectomy. At age 30, she was then found to have multiple uterine tumors requiring hysterectomy. In 2017, she underwent CT abdomen for suspected appendicitis, which revealed multiple renal cysts and hepatic hemangiomas. In 2019, patient was found to have recurrent parathyroid adenoma and underwent revision parathyroidectomy. Pathology revealed hypercellular parathyroid gland consistent with adenoma. Based on constellation of symptoms, HPT-JS was suspected. Patient was referred to genetic counselor. Detailed family history revealed multiple family members affected by malignancies including melanoma, breast cancer, prostate cancer, liver cancer and two cousins with suspected MEN1. She underwent testing for hereditary hyperparathyroidism and melanoma including CDC73 gene. All genetic testing was surprisingly unrevealing. Discussion: CDC73 gene (also known as HRPT2 gene) is responsible for the pathogenesis of HPT-JT. While HPT-JT itself is a rare condition, 60% of patients affected by it, harbor the HRPT2 gene mutation. About 10–15% of these individuals are affected by parathyroid carcinoma. HRPT2 mutated parathyroid adenomas also seem to have some malignant potential. The autosomal dominant inheritance of HPT-JT makes gene testing important since it has implications for other family members and carries weight in clinical management of genetic carriers. Therefore patients with extensive personal or family history of malignancy should be followed closely. Endocrinologists should have a low threshold to refer such patients for genetic counseling and testing. However genetic testing also has its limitations and can only explain 50–75% of cases of HPT-JT syndrome. Hence, even though our patient has a negative genetic screen, the possibility of HPT-JT is not complete ruled out.

Trabecular Juvenile Ossifying Fibroma of the Craniofacial Skeleton: Etiopathogenesis and a Case Report of the Rare Entity

ABSTRACT The term, fibro-osseous lesions, is used for a group of pathological disturbances encompassing developmental, reactive or dysplastic lesions and neoplasms characterized by replacement of normal bone architecture by tissue composed of collagen fibers and fibroblasts containing various amount of calcified tissue. The groups of the fibro-osseous lesions are best considered as a spectrum of processes arising from cells in the periodontal ligament. Juvenile ossifying fibroma (JOF) is a benign, but potentially aggressive, fibro-osseous tumor of the craniofacial bones. This uncommon neoplasm is distinguished from other fibro-osseous lesions primarily by its age of onset, clinical presentation, potential behavior and the high tendency to recur. Clinically presenting as an actively growing lesion. Histopathologically consists cell rich fibrous stroma containing bands of cellular osteoid without osteoblastic lining together with trabeculae of more typical woven bone. Pathogenesis of JOF may be related to mutations of HRPT2 gene which may arises due to haploinsufficiency of the HRPT2 gene. Here, we reported a case of trabecular JOF (TJOF) which had variations in clinical, radiographic features and histopathological characteristics and it's etiopathogenesis in detail. How to cite this article Kadam R, Patel S, Pathak J, Swain N, Kumar S. Trabecular Juvenile Ossifying Fibroma of the Craniofacial Skeleton: Etiopathogenesis and a Case Report of the Rare Entity. J Contemp Dent 2014;4(1):51-55.

Parathyroid Pathology: Hyperparathyroidism and Parathyroid Tumors

Context.—Primary hyperparathyroidism is the most common cause of hypercalcemia in the outpatient setting. Parathyroid adenomas are common, unlike other parathyroid tumors. This review presents a brief summary of current updates in parathyroid pathology. Objective.—To review parathyroid development and discuss issues in hyperparathyroidism and diagnosis of parathyroid lesions, including the application of immunohistochemistry and molecular biology. Data Sources.—Current texts, PubMed (National Library of Medicine) articles, and Memorial Sloan-Kettering Cancer Center archives. Conclusions.—Primary hyperparathyroidism is most commonly seen with sporadic adenomas, followed by hyperplasia, multiple adenomas, and carcinoma. Autosomal dominant familial hyperparathyroidism syndromes should be considered in the evaluation of patients with parathyroid lesions, particularly in association with parathyroid carcinoma. While the incidence of parathyroid carcinoma is quite low, it is seen with a greater frequency in those patients with hyperparathyroidism-jaw tumor syndrome. Inactivation of the tumor suppressor gene HRPT2 can be identified in a large number of parathyroid carcinomas. Hence, germline HRPT2 gene mutations may reflect unrecognized syndromic patients.

Jaw Tumor: An Uncommon Presenting Manifestation of Primary Hyperparathyroidism

ABSTRACT Introduction To report two unusual cases of primary hyperparathyroidism (HPT) that initially manifested with a “ jaw tumor” and to discuss the clinical implications of a giant cell granuloma vs an ossifying fibroma of the jaw. Material and methods The history, physical examination, laboratory values and the imaging and pathologic findings are described in two patients who presented with a “jaw tumor” and were subsequently diagnosed with primary HPT. The diagnosis and management of osteitis fibrosa cystica and HPT-jaw tumor syndrome are reviewed. Results Patient #1 was a 70-year-old male who presented with hypercalcemia, severe jaw pain, and an enlarging mass in his mandible. Biopsy of the mass revealed a giant cell tumor and he was subsequently diagnosed with primary HPT. A sestamibi scan demonstrated a single focus of abnormal radiotracer accumulation, corresponding to a 13,470 mg parathyroid adenoma, which was resected. Postoperatively, the serum calcium normalized and the giant cell granuloma regressed spontaneously. Patient #2 was a 36-year-old male with four incidentally discovered tumors of the mandible and maxilla, who was diagnosed with normocalcemic HPT and vitamin D deficiency. Biopsy of one of the tumors revealed an ossifying fibroma. Bilateral neck exploration revealed a 2480 mg right inferior parathyroid adenoma, which was resected. Postoperative genetic testing revealed an HRPT2 gene mutation. He subsequently underwent resection of an enlarging ossifying fibroma of the mandible with secondary reconstruction. Conclusions A “jaw tumor” in a patient with primary HPT may be a manifestation of osteitis fibrosa cystica or HPT-jaw tumor syndrome underscoring the importance of biopsy and genetic testing for management and follow-up.

HRPT2-related familial isolated hyperparathyroidism: could molecular studies direct the surgical approach?

It is still debatable which is the best management to familial forms of hyperparathyroidism. Conservative, minimally invasive or aggressive surgical approaches have been proposed from different groups around the world. Our objective was to study the gene mutation, expression of HRPT2 and the clinical outcome after 32 years of follow-up in one Brazilian kindred with familial isolated hyperparathyroidism (FIHP). Clinical and biochemical data, direct sequencing of the HRPT2 gene, analysis of parafibromin expression using RT-PCR, and immunohistochemistry were done. A nonsense mutation was found in exon 1 (c.96G>A)(p.Trp32X) in all affected members studied. Using RT-PCR, mRNA transcription was altered with complete absence of both transcripts in tumor tissue. Immunohistochemical analysis of tumors showed loss of parafibromin immunoreactivity. In this kindred there was a high prevalence of recurrence (75%), or persistence after less than subtotal parathyroidectomy that led us to consider a more aggressive surgical approach should be discussed among the affected family members, once surgical criteria was met. We concluded that it is necessary to individualize the surgical approach for HRPT2-related hyperparathyroidism until we can gather a better phenotype-genotype correlation in larger series, to best define their treatment.

Different somatic alterations of the HRPT2 gene in a patient with recurrent sporadic primary hyperparathyroidism carrying an HRPT2 germline mutation

Early onset of primary hyperparathyroidism (PHPT) and multiglandular involvement suggest a familial form in which germline mutation of a PHPT-related gene(s) and a somatic event at the same locus can be often demonstrated. We investigated the involvement of multiple endocrine neoplasia type 1 (MEN1) and HRPT2 genes in a 39-year-old man with recurrent PHPT. PHPT was firstly diagnosed at the age of 21 and the patient had two recurrences separated by extended periods of normocalcemia. This unusual history prompted us to investigate other family members and study the MEN1 and HRPT2 genes. An HRPT2 germline missense mutation in exon 3 (R91P) was found in the index case, which was associated with different HRPT2 somatic alterations in each of the three examined parathyroid tumors. These findings are consistent with Knudson’s ‘two hit’ concept of biallelic inactivation of classical tumor suppressor genes. Screening of 15 asymptomatic relatives was negative for the R91P germline mutation. All the three abnormal parathyroid specimens showed cystic features at histology and were negative for parafibromin immunostaining. In one specimen, diffuse parafibromin staining was evident in a rim of normal parathyroid tissue surrounding the adenomatous lesion. Our study shows that different somatic genetic events at the HRPT2 locus are responsible for the asynchronous occurrence of multiple adenomas in a patient carrying an HRPT2 germline mutation. The finding of diffuse parafibromin staining in a rim of normal parathyroid tissue, but not in the contiguous adenomatous lesion, reinforces the concept that loss of parafibromin expression is responsible for the development of parathyroid tumors in this setting.